Molecular layer ectopias and microgyria have been seen in the brains of dyslexic subjects. Immune-defective mice spontaneously develop molecular layer ectopias, and we have successfully induced microgyria in rats and mice. Both humans and animals with these minor cortical malformations exhibit behavioral abnormalities. Preliminary findings have shown that both the spontaneous (SMM) and the induced (IMM) malformations are associated with a more widespread cortical disorganization than is readily apparent. We suspect that it is this architectonic and connectional disorganization that is responsible for the behavioral abnormalities. In the present research, we propose to show the extent of cellular changes associated with SMM and IMM and the connectional changes associated with IMM. We will examine SMM from the breeding Core as well as from the Embryo Transfer research, the latter to look for effects of uterine manipulations on the final structure of the SMM. We will examine IMM that have been produced by varying timing and severity of injury at the onset, to assess these factors with respect to the final structure of the IMM. Minor cortical malformations in humans are receiving increasing attention, but their etiology and significance are unknown. We have seen them to be related to at least one form of learning disability -- developmental dyslexia. We expect that this research will shed light on the nature of the cortical malformations and their possible consequences on behavior.